1. Field of the Invention
The present invention relates to an electronic unit such as a ROM pack for use in an electronic teaching machine, an electronic translating machine or an electronic desk-top calculator.
2. Description of the Prior Art
A prior art electronic unit such as a ROM pack is usually constructed in a following manner. A plurality of printed circuit boards having elements such as LSI chips packaged thereon are stacked in an outer casing and the printed circuit boards are interconnected by flexible cables, or a flexible printed circuit board is folded and rigid substrates are backed at mounting areas of the elements such as LSI chips and the printed circuit board is housed in an outer casing.
However, in such a prior art ROM pack, the interconnection of the printed circuit boards or the backing of the rigid substrates is troublesome work and hence the assembling work is time-consuming. In addition, since the components cannot be readily removed because of the structure, exchange of components in case of trouble is troublesome. Furthermore, since expensive components must be used, the cost is high.